Pump



April 26, 1966 J. F. CAMPBELL. 3,247,800

PUMP

Original Filed July 2, 1959 7 Sheets-Sheet 1 FREE WHEELING RANGE POWERRANGE INVENTOR. JOHN E CAMPBELL ATTOR NE YS April 26, 1966 J. F.CAMPBELL 3,247,800

PUMP Original Filed July 2, 1959 7 Sheets-Sheet 3 5 FIG. 5

INVENTOR. JOHN E CAMPBELL ATTORNEYS April 26, 1966 J. F. CAMPBELL3,247,800

PUMP

Original Filed July 2, 1959 7 Sheets-Sheet 4 FIG. 7

I88 I y 39 205 fl I87 1'85 \t '97 IBTA 1 FIG I4 ee \L 5? FIG. I5

22 INVENTOR.

JOHN E CAMPBELL M, MI QM "M ATTORNEYS April 1966 J. F. CAMPBELL3,247,800

PUMP

Original Filed July 2, 1959 '7 Sheets-Sheet 5 F|G.|8 FIG. 20

FIG. l6

ATTOR N EYS April 26, 1966 J. F. CAMPBELL 3,247,800

PUMP

Original Filed July 2, 1959 7 Sheets-Sheet a FIG. 2|

INVENTOR. JOHN E CAMPBELL AT TO R N EYS April 26, 196$ J. F. CAMPBELL3,247,800

PUMP

Original Filed July 2, 1959 '7 Sheets-Sheet 7 so pnsssm CHSBB was so Xmess, zvs

o moo zcoo 5000 4000 5050 ENGINE RPM PTA FIG. 27

VAC, ms. H6 1 ENGINE RPM VAC INS. HG

FIG. 28

mess, PSI

INVENTOR. JOHN F. CAMPBELL will drums, are not required.

United States Patent PUMP John F. Campbell, Beech Knoll, TimheridgeTrail, Gates Mills, Ohio Original application July 2,1959, Ser. No.824,506, now Patent No. 3,059,416, dated Oct. 23, 1962. Divided and thisapplication Aug. 29, 1962, Ser. No. 220,243 13 Claims. (Cl. 103-417)This application represents a divisional application of my copendingparent application entitled Fluid Drive and Brake System, Serial No.824,506, filed July 2, 1959, now Patent No. 3,059,416, issued October23, 1962.

The present invention relates generally, as indicated, to a pump andmore particularly to a pump assembly for a fluid drive and brake systemfor a power transmission and braking in motor vehicles such as passengercars, trucks, buses, etc.- More particularly, the present inventionrelates to an all-fluid power transmission system characterized in thatthe conventional transmission, differential, live axle, and the separatehydraulic brake system, with its master cylinder, wheel cylinders, brakeshoes and brake In such fluid power transmission system, a prime mover,be it an internal combustion engine, a diesel engine, a steam or gasturbine, a dynamoelectric machine, or the like, drives such fluid pumpassembly and, in turn, such pump assembly drives a fluid motor systemwhich, in the case of a motor vehicle, comprises rotary fluid motorsmounted in the rear wheels, or in the front wheels, or preferably in allthe wheels.

Numerous attempts have been made heretofore to provide such hydraulicpower transmission wherein an enginedriven pump supplies wheel mountedmotors, but to my knowledge, these all have had the serious shortcomingof either lack of proper control of capacity or speed, or of pooroverall operating efiiciency owing to a variety of dif ferent reasonssuch as hydraulic slip, restriction of the pump inlet to achievecontrol, changing of engine load by changing of power absorbed by thepump, lack of relation of pump capacity to the variables attuned toeflicient engine operation, lack of coordination of engine rpm. andcarburetor throttle position or manifold pressure for eflicient engineoperation, etc.

It is accordingly a principal object of this invention to provide suchfluid drive and brake system which comprises an engine-driven variabledelivery positive displacement pump and fluid motors driven by the pump,the pump being provided with control means effective to provide foreflicient operation of the engine under all conditions of engine speedand load.

Other objects and advantages of the present invention will becomeapparent as the following description proceeds.

To the accomplishment of the foregoing and related ends, the invention,then, comprises the features hereinafter fully described andparticularly pointed out in the claims, the following description andthe annexed drawings setting forth in detail certain illustrativeembodiments of the invention, these being indicative, however, of a fewof the various ways in which the principle of the invention may beemployed.

In said annexed drawings:

FIG. 1 is a side elevation view of my power transmission 1pgmpgassemblyas viewed from the right-hand end of FIG. 5 is a cross-section view, onsomewhat enlarged scale, taken substantially along the line 5-5, FIG. 4;

FIGS. 6 to 15 are detail cross-section views taken respectively alongthe lines 66, FIG. 5; 7-7, FIG. 4; 8 -8, FIG. 5; and 99, 101tl, 11-11,1212, 1313, FIG. 4; 14-14, FIG. 3; and 1515, FIG. 4;

FIG. 16 is a central diametrical cross-section view showing a preferredform of wheel-mounted fluid motor;

FIG. 17 is a transverse cross-section view taken substant-ially alongthe line 17-17, FIG. 16;

FIGS. 18 to 20 are detail cross-section and developed views of thepreferred form of valving employed in connection with the pump of theengine-driven pump assemy;

FIGS. 21 to 24 are cross-section views and developed views illustratingthe preferred form of valving employed in each wheel mounted fluidmotor;

FIG. 25 illustrates a further modification wherein manifold vacuum isemployed to provide certain control characteristics; and

FIGS. 26 to 28 are graphs with engine r.p.m. plotted against pressurep.s.i. (FIG. 26) and presssure p.s.i. plotted against manifold vacuum ininches mercury (FIGS. 27 and 28).

I. The fluid drive and brake system as a whole 1 (FIGS. 1 and 2Referring to FIG. 1, there is shown therein in dot-dash lines a typicalpassenger car 1 with which the present invention may be used to driveand to brake the four wheels 2, said car being powered as by aspark-ignition, four-cycle engine 3 and being steered as by a steeringwheel 4. Operatively connected between the engine 3 and fluid motors(not shown in FIG. 1) mounted in the wheels 2 is the hydraulic unit 5which transmits engine power to the wheels and which is controlled as bythe foot-operated pedal 6 in the car 1. The pedal 6, as later described,also serves as the brake pedal to effect braking of the wheels 2.Although the unit 5 is herein shown mounted on the rear end of theengine block it may be mounted at any convenient place for driving bythe engine crankshaft. Because the engine power is transmitted to thewheels '2 by way of fluid lines there is no need for the usualdifferential and live axles, nor for the universal joints andconventional drive shaft. Thus, substantial economies in cost and weightare effected and the floor of the passenger compartment need not havethe usual longitudinal tunnel.

Referring to FIG. 2, one of the main elements of the present system,i.e. the hydraulic unit 5, the wheel motors, and the control elementsfor the engine 3 and unit 5 is the engine-driven variabledelivery'positive displacement pump 1%, the capacity of which may bevaried from zero to maximum in accordance with the fluid pressure in thepump control line 11 leading thereto. The pump inlet line 12communicates with a vented sump 13 and the pump output line 14 leads tothe respective motors 15 mounted in the vehicle wheels 2 by way of acheck valve 16, a forward and reverse control valve 17, and either line19 or 20 depending on whether the wheel motors 15 are to be driven topropel the vehicle 1 in a forward or a backward direction. The other ofsaid. lines 19 and20 is the return line through which the spent fluid isreturned to the sump 13 through valve 17, return line 18, brake valve21, and heat exchanger 22. Ta 23 or the like may be provided so that thefront wheels may be operated by one pair of lines 19 and 20 and so thatthe rear wheels may be similarly connected with another pair of lines 19and 211 (not shown in FIG. 2). As is later described,

a) the delivery capacity of pump is preferably directly proportional tothe fluid pressure in the line 11.

Downstream of the check valve 16 is a relief valve 24 which is normallyclosed and set to open only when the discharge pressure from the pumpll? is greater than the maximum operating pressure of the system.

The forward and reverse control valve ll7is normally in the forwardposition when the solenoid 25 thereof is in deenergized condition.However, when the lever 26 of the ignition switch 27 is in the Onposition and the lever 29 of the direction switch 28 is turned to the R(reverse) position, the solenoid 25 will be energized to actuate thevalve 17 so as to reverse it and thus the wheel motors will be driven inreverse direction.

As shown in FIG. 2, each wheel 2 is mounted on a strut assembly 3.!)which allows the wheel shaft 31 to move up and down as the vehicle 1travels on rough road. In the case of the front wheels 2, the mountingstrut 32 may be rotated about its axis by a steering lever 33 adapted tobe operatively connected to steering wheel 4 by conventional means.Thus, when the valve 17 is in forward F position, fluid under pressurewill enter the fluid motor by way of the line 19 and the spent fluidwill be returned to the sump 13 by way of the other line and return line18; and, of course, when the solenoid of said valve 17 is energized, asaforesaid, fluid under pressure will be supplied to each motor 15through the line 29 to cause the motor 15 to be driven in a backward orreverse direction, and again the spent fluid will be returned to thesump 13 by way of the other line 19 and return line 18.

Referring now to the control system, there is provided a pivotallymounted foot pedal 6 which, through linkage 34, actuates a cam shaft 35,the pedal 6 in FIG. 2 being shown in its'intermediate Free WheelingRange. When it is desired to increase the engine r.p.m. and poweroutput, the pedal 6 is depressed to the Power Range and when it isdesired to brake the vehicle 1, the pedal 6 is swung upwardly to theBrake Range. Operated by the cams 36 on the cam shaft 35 is the enginethrottle control assembly 37 which, as hereinafter explained, opens thethrottle valve 38 according to a predetermined schedule as the pedal 6is depressed through the Power Range. The second cam 39 operates thebrake valve 21 when the pedal 6 is swung counterclockwise to the BrakeRange position and, in essence, the brake valve 21 is a variablerestrictor which progressively blocks the return of fluid from the wheelmotors 15. Because the fluid is heated thereby, especially during quickstops, the heat exchanger 22 is provided ahead of the sump 13.

The third cam 40 on the cam shaft 35 controls operation of the pump it)as is presently to be explained, and the fourth cam 41 controlsenergization and deenergization of the solenoid 42 of a pump unloadingvalve 43.

Also driven by the engine 3 is an r.p.m. pump 45 which has its intakeport in communication with intake line 12 and which has its deliveryport connected to output line 46 leading to a chamber at one end ofvalve 47 and from the chamber into a preload check valve 53 which has anorifice or restriction 49 associated therewith.

As later explained, the capacity of the pump 45, the size of the orifice49, and the size of the seat, the contour of the valve member, and thepreload and rate of deflection of a spring within the check valve 48 areso designed as to achieve the desired program of pressure in the chamberof valve 47 versus the movement of the pedal 6. This is represented bythe curve 124 in FIG. 25. In essence, the pressure in the valve chamberaforesaid may be said to be an indication of the actual r.p.m. of theengine drive shaft while the pressure in another chamber at the otherend of said valve 47 is an indication of the desired r.p.m. of theengine drive shaft.

The engine drive shaft also drives a servo pump 51 which has its intakeand delivery ports connected to intake line 12 and delivery line 52, arelief valve 53 serving to establish a constant pressure fluid supply tothe variable restrictor valve 54 which is operated by cam 46. When theactual r.p.m. of the engine drive shaft is greater than that desired, asestablished by the variable restrictor valve 54 and orifice the pressurein chamber 139 will be greater than in the other chamber 133. The lowerpressure leading into the right end of valve 47 through line 57 willrender .the predominant pressure in the left end through line aseffective to cause the valve member in valve 47 to move in one directionso as to allow fluid to flow under pressure through the line 58 and theunloading valve 43 to the variable capacity pump line 11 from the servopump output line 52. Accordingly, the amount of fluid pumped by the pump10 will increase to thereby decrease the speed of the engine driveshaft.

Conversely, when the actual r.p.m. of the engine drive shaft is lessthan that desired as indicated by the setting of valve 5 5, the pressurein chamber 138 will build up whereby the then predominating pressure inthe right chamber of valve 47 will cause the valve member to move in theopposite direction. This allows the fluid undr pressure in the pumpcapacity control line 11 to be bled into the return branch 59 of thereturn line 18. The lowering of the pressure in the line H causes adecreased amount of fluid to be pumped by the pump It) therebyincreasing the r.p.m. of the drive shaft.

In general, the operator sets up the desired r.p.m. through the positionof the foot pedal 6 while simultaneously valve 47 operates automaticallyto increase or decrease the torque on the engine drive shaft therebymaking the actual r.p.m. agree with the desired r.p.m.

When the solenoid 42 of the unloading valve 43 is energized either byshifting the lever 28 of direction switch 29 to neutral position N or byshifting the pedal 6 to Free Wheeling Range with cam 41 closing switch60, capacity control line 11 is vented through branch return 61 toreturn line 18 whereby pump llt) operates at zero capacity. Displacementof the fluid motors 15 is accommodated by the free-wheeling check valve62 connected between intake line 12 and delivery line 14 which leads toforward and reverse control valve 17.

Having thus described the general structure and operation of the systemherein, reference will be made under appropriate headings of the detailsof the several components of the system.

Engine-driven pump assembly (FIGS. 3, 4 and 5) and components thereof(FIGS. 6 to 15 and FIGS. 18 to 20) As best shown in FIGS. 3, 4 and 5,the engine-driven pump assembly or hydraulic unit 5 has a shaft 65journalled therein, as in needle bearings 66 or the like, and adapted tobe coupled with the crankshaft of the engine 3 in the case of aninternal combustion engine and, of course, with a comparable orequivalent output or drive shaft of an electric motor, gas turbine,diesel engine, etc. This unit 5 comprises a two-part housing including amain casting 67 and a cap part 68 secured together by screws 69, the cappart 63 being formed with a vented filler cap 70 leading into the hotoil gallery '71.

Formed in the hydraulic unit 5 is the sump 13 of annular form with fluidreturned thereto through a filter 72 and heat exchanger 22 alsopreferably annular in form, and upstream of the filter 72 is a hot oilgallery 71 to which the spend fluid in heated condition, is returned forflow through the filter 72 and heat exchanger 22 into the sump. The heatexchanger 22 as best shown in FIGS. 5 and 15 may have cooling fluidcirculated therethrough by way of the openings 73 and 74 formed incasting 67.

The variable deliver positive displacement pump 10 (FIG. 5) and pumpinlet valvz'ng (FIGS. 5 and 18 to 20) shaft, actuates a plurality ofspring-biased radial plungers 82, herein six such plungers beingemployed. Each plunger 82 is guided for radial movement in a bushing 83which preferably is shrunk fit in a radial bore in the housing part 67and retained by snap ring 84. The bushing is helically grooved, asshown, to retain the tension spring 85. The plunger 82 is a slip fit inthe bore of a capacity regulator sleeve 86 and the outside diameter ofthe sleeve is a slip fit in the radial bore of housing part 67.The'capacity regulator sleeve 86 also is helically grooved to retain theother end of the tension spring 85.

In FIG. 5 the sleeve 86 is shown in a position for 50% pump deliverycapacity by reason of fluid pressure in the chamber 87 acting on theradially outer end of sleeve 86, thereby elongating the tension spring85 and urging the inner end of sleeve 86 to a position such that whenthe plunger 82 has moved in one-half of its stroke against eccentric 80by biasing spring 88, the spill groove 89 thereof will be inward of theinner end of sleeve 86. Thus, during the first half of the outwardpumping stroke of the plunger 82 the fluid in the chamber 90 will flowthrough the spill groove 89 into chamber 91 and thence through passage92 into the sump 13. When the pressure in the chamber 87 and in the line11 (passage 11A, manifold 11B, and passage 11C) leading thereto fromsolenoid valve 43 and passage 58 is at a high value, the sleeve86 willcontact the stop surface 93 and will thereby assume a position for 100%pump delivery capacity, that is, the spill groove 89 is within sleeve 86during the entire outward pumping stroke of plunger 82. On the otherhand, when the pressure in the chamber 87 and line 11 (11A, 11B, and11C) is at a low value, the sleeve 86 will move outward under theinfluence of the tension spring 85 so as to contact inner end of bushing83 whereby it is then in the zero pump delivery capacity position withthe spill groove 89 inward of the inner end of the sleeve 86 during theentire pumping stroke. Accordingly, the position of sleeve 86 and,therefore the pump delivery capacity, is directly proportional to thepressure in the line 11 and chamber 87.

The volume of fluid pumped by each plunger 82 is a constant amountduring each revolution of the drive shaft 65, however, the portion ofthe volume pumped through the delivery check valve 16 is dependent uponthe position of the associated sleeve 86 and thus, on the pressure inthe line 11. For example, with the sleeve in the 50% capacity position,as shown in FIG. 5, fluid in each plunger chamber 90 is in commoncommunication with chamber 91 when the plunger 82 is at any positionbetween the bottom end of its stroke and 50% of the maXimum outwardstroke, and thus the spill groove 89 will be uncovered and the fluid inthe cavity 90 will pass freely into chamber 91 and thence through thepassage 92 which leads into sump 13. This is true whenever spill groove89 is uncovered by the inner end of sleeve 86 because the resistancethrough the above circuit to the sump 13 is much less than through theassociated delivery check valve 16 which is always biased shut by thecombination load of the spring 93 and the operating pressure in thedelivery line 14 (manifold 14A and the pressure passages 14B leading toforward and reverse control valve 17). According to the above, it can besimilarly reasoned that when the capacity sleeve 86 is in the outermostzero capacity position, that is, in contact with the end of bushing 83,the spill groove 89 will be uncovered throughout the entire stroke ofthe plunger 82 and, therefore, all the fluid which is displaced duringthe inward stroke will return to the sump 13. On the other hand, whenthe capacity sleeves 86 are in the 100% capacity position, that is, incontact with the stop surfaces 93, the spill grooves 89 thereof will becovered throughout the entire pumping strokes of the respective plungers82 and, therefore, all of the fluid displaced by respective plungers 82will pass through the respective check valves 16 and into the manifold14A and thence through passage 14B to the forward and reverse controlvalve 17.

The pump inlet valve 95 is drivenv by the drive shaft 65 and as bestshown in FIGS. 5 and 18 to 20 the inlet valve port 96 is open to theinlet passages 97 only during the suction strokes of the respectiveplungers 92. Fluid is supplied through the port 96 without restrictionfrom line 12 (opening 12A in valve 95 which opens into sump 13).

The pump inlet valve 95 as shown in detail in FIGS. 18 to 20 has theport 96 through the wall thereof and rotates in a sleeve 98 which may beshrunk fit in the housing part 67, said valve 95 being driven throughthe splined connection of the valve drive shaft 99 which, in turn, has asplined connection with the pump drive shaft 65. A development of theoutside diameter of the sleeve 98 is shown in FIG. 19 and a developmentof the outside diameter of the valve 95 is shown in FIG. 20. Multiplepassages 100 registering with pump intake passages 97 are connected tomultiple static holes 101 by grooves 102 respectively. The grooves 102connect passages 100 and holes 101, which are spaced 180 apart aroundfrom the passage. The area of each pair of holes 101 is equal to thearea of the diametrically opposite passage 100. By reason of thatconstruction, the hydraulic forces on the surface of the valve 95 areopposed by equal and opposite forces and therefore, are balanced out.This allows the valve 95 to rotate freely in the bore of the sleeve 98regardless of the pressure in the ports 97 and in the passages 100. Thechamber 12A in the valve 95 receives fluid from the sump 13 and thisfluid is drawn through the port 96 and flows through the multiplepassages 100 and related ports 97 to the respective pump chambers as thevalve rotates to align the opening 96 with successive passages of sleeve98.

The solenoid valve 43 (FIG. 7; also FIGS. 2-5) This valve 43 is formedas a part of the housing member 68 including a ported sleeve 105 andsolenoid 42. held therein as'by means of snap rings as shown, the sleeve105 and the solenoid retainer 106 being provided with suitable packingrings such as O-rings, to prevent leakage. The ported sleeve 105 isintersected by a pair of passages 58 and 11A, of which the passage 11A,best shown in FIG. 5, extend through the housing part 67 to an annularmanifold 11B, and thence through radiating passages 11C to therespective chambers 87 associated with capacity regulating sleeves 86,whereby such passages 11A, 11B, and 11C constitute the pump capacitycontrol line 11 referred to in connection with FIG. 2. The other passage58 communicates with a port of the valve 47 as shown in FIG. 2 and asshown in detail in FIG. 11.

Reciprocable in the ported sleeve 105 is the valve spool 107 which isbiased to the position shown by the spring 108, the stem 109 of thevalve spool extending into the solenoid 42 so as to constitute anarmature which is pulled toward the right when the solenoid 42 isenergized, as hereinafter explained. When the solenoid 42 isdeenergized, fluid under pressure entering from passage 58 flows aroundthe groove of the spool 107 to the passage 11A.

When the solenoid 42 is energized the valve spool 107 is pulled towardthe right to block such flow of fluid from passage 58 to passage 11A andto open the passage 11A to the hot oil gallery 71 by way of the open endof the ported sleeve 105. The solenoid 42 is thus energized when thedirection switch lever 28 (FIG. 2) is moved to the neutral N positionand is also so energized when the pedal 6 is moved to Brake Rangeposition or to Free Wheeling Range, whereby the cam 41 on the cam shaft35 closes the switch 60 which is wired in parallel with the aforesaidneutral N position of the direction switch 29.

The check and restriczor valve 4849 (FIG. 10; also FIGS 2,4 and 8) Thisvalve is in the nature of a pressure regulating valve also formed in thehousing part 68 and including a ported sleeve 115 held in place by asealing plug 116 and snap ring 117 and provided with outlet ports 118leading into the hot oil gallery 71 and an inlet 46 from r.p.m. pump 45and valve 47 (FIGS. 2, 8, 10, and 11). The valve member 11? is providedwith a guide stem 12! and a head 121 which has a clearance in sleeve 115to form the orifice 49. The valve member 119 is biased by means of aspring 122 which, through a headed wire 123 secured to the valve member,normally tends to urge the latter to the position shown in FIG. 10. Asthe pressure in the passage 46 builds up the valve member 119 is urgedto the left to bleed off an increasing volume of the fluid to the hotoil gallery '71 so as to maintain a prescribed pressure in the line 46and in the chamber at the left end of valve 47 (FIG. 11). The capacityof rpm. pump 45, the size of the orifice 49, the size and contour of thevalve head 121, and the preload and deflection rate of the spring 122are selected to establish the program of pressure in line 46 versusmovement of pedal 6 as represented by line 124 in FIG. 25.

The valve 47 (FIGS. 10, 11; also FIGS. 2, 3, 4 and 8) This valve 47, asthe others, is formed as a portion of the housing part 68 and has aported sleeve 136 therein which is formed with openings in register withpassage 46 from the r.p.m. pump 45, with passage 52 from the servo pump51, with passage 58 to valve 43, with return branch 59 to the hot oilgallery 71, and with passage 57 to the variable restrictor 54.

The ported sleeve 139 is closed at its ends by the spring abutmentmembers 131 that are held in place together with sleeve 130 as by meansof snap rings 132. Centered in the ported sleeve 130 by springs 133 isthe valve spool 134 provided with three lands 135, 136, 137 and a pairof intervening grooves.

When the spool 134 is in its centered position as in FIG. 11, thepassage 58 is blocked by the middle land 136. When the pressure in thepassage 57 and chamber 138 acting on the right-hand end of the spool 134is greater than the pressure in the passage 46 and chamber 139 acting onthe left-hand end, the spool 134, the latter will be shifted toward theleft to establish metered flow (by reason of the metering portions ofthe middle land 136) from passage 58 to passage 59 thereby bleeding thecontrol line 11 (11A, 11B, and 11C). On the other hand, when thepressure in the chamber 135 acting on the left-hand end of the spool 134is greater than the pressure in the chamber 138 acting on the right-handend, the spool 134 will be shifted toward the right to establish meteredflow from passage 52 to passage 58 to build up a desired controlpressure in line 11.

The operation of this valve 47 in establishing the pressuredifl'erentials aforesaid in chambers 138 and 13) at the opposite ends ofthe spool 134 is controlled by the cam actuated regulating valve orvariable restrictor 54, which is next to be described, and by the valve48.

The cam actuated regulating valve 54 (FIG. 12; also FIGS. 2 and 8) Thisvalve comprises a ported sleeve 145 held in place in the housing part 68by means of snap rings as shown and mounted on the pedal operated camshaft 35 is the cam 40 which engages the end of a metering valve 146which is biased by spring 147 against the cam 40. Said metering valve146 is provided with an intermediate neck and adjoining conical surfacewhich cooperates with the passage 14% to vary the size thereof accordingto the position of the cam 40 and metering valve 146. Thus, when the cam40' is swung in the clockwise direction, as viewed in FIG. 12, thetapered metering portion of the metering valve 146 will graduallyrestrict the fiow of fluid from passage 57 through chamber 56 andthrough passage 143 into the hot oil gallery 71.. The passage 57 justreferred to is the same passage 57 that communicates 8 with the chamber138 at the right-hand end of the spool 134 of the valve 47 in FIG. 11.

The passage 52 from valve 47 and servo pump 54 leads to the chamber 55upstream of the orifice 149 and therefore fluid flows through thechamber 56 and passage 148 into the hot oil gallery 71 through ports 156of the sleeve when the metering valve 146 is partly or fully open asshown in FIG. 12. Of course, when the metering valve 146 is only open aslight amount such that the flow area of passage or variable orifice 148is less than the flow area of the orifice 149, fluid pressure will buildup in the chamber 56 and passage 57 which leads to the right-hand end ofthe spool 134 of the valve 47 in FIG. 11 to thus urge the spool 134-toward the left. This will be described in detail.

The pumps 45 and 5] and the regulating valve 53 associat d with thelatter (FIGS. 2, 5, 8 and 9) The r.p.m. pump 4-5 and the servo pump 51are gear pumps arranged in tandem and driven by a shaft which is coupledto the rotary pump inlet valve drive shaft 99, which, in turn, iscoupled to the engine-driven pump drive shaft 65. The shaft 155 is keyedto one of the pair of meshing gears 156 of the pump 45 and to one of thepair of meshing gears 157 of the pump 51.

These pumps 45 and 51 have intake ports 158 and 159 respectively whichcommunicate with the sump 13 and delivery ports 160 and 161 which by wayof the previously referred passages 46 and 52, communicate respectivelywith the valves 47 and 48-49, and the valves 47 and 53, as best shown inFIG. 8.

The regulating or relief valve 53 associated with the servo pump 51 isin the nature of a ball relief valve connected in parallel with the pump51 as clearly shown in FIGS. 2, 8, and 9. The ported sleeve 165 of valve53 is held in place by the plug 166 and snap ring 167 and has a seat forthe ball 168 which is biased by spring 169 to closed position and whichis adapted to be unseated to open communication between the deliverypassage 52 from pump 51 and the return branch 59 that leads to the hotoil gallery 71 to maintain a prescribed pressure of the fluid deliveredby the pump 51. In other words, the ball 168 is in seated positionexcept when the pressure of the fluid delivered by the pump 51 isgreater than a predetermined maximum as determined by the bias of thespring 169. Such spring bias may be increased or decreased as desired bysubstituting spring backup disks 170 of different thicknesses betweenthe spring 169 and the aforesaid plug 166.

The direction control valve 17 (FIGS. 2 t0 6) The body of this valve isformed in the housing part 68 including a bore therethrough intersectedaxially therealong by a pressure inlet passage 143; a pair of servicepassages 20; a return passage 18; and another pair of service passages.19.

Reciprocable in the bore 175 is a valve spool 176 biased to the right asviewed in FIG. 6 by means of the spring 177 that is compressed betweenthe solenoid assembdy 25 and the valve spool 176. In this position,which is the forward drive position, fluid under pressure deliveredthrough passages 14A and 14B from the variable capacity, positivedisplacement pump 10 flows through the service passages 20 to thewheel-mounted fluid motors 15 to drive the wheels 2 to propel thevehicle 1 forwardly. When the solenoid 25 is energized by turning thedirection switch lever 28 to the reverse R position, the spool 176 willbe pulled to the left, as viewed in FIG. 6, thereby closingcommunication between the inlet and the forward passages 14B and 20 andestablishing communication between the inlet passages 14B and thereverse passages 19 by way of the chamber 178 at the left, axialcross-over passage 179 from chamber 178 to the chamber 180 at theright-hand end of the valve 17 to passages 19 whereby the wheel motors15 and wheels 2 will be driven in the opposite direction to propel thevehicle 1 rearwardly.

When the spool 176 is in the forward position (solenoid 25 deenergized)the fluid displaced by the fluid motors returns through the servicepassages 19 into the return passage 18 to the sump 13 by way of the openbrake valve 21 which is shown in FIGS. 2 and 13, and similarly, when thespool 176 is in the reverse position (solenoid 25 energized) thedisplaced fluid from the wheel motors 15 flows through the servicepassages 20 to the return passage 18 and thence to the sump 13 by Way ofthe open brake valve 21.

The ends of the valve bore 175 are closed by plugs 181 and 182 which areretained in place by snap rings or the like.

The brake valve 21 (FIGS. 2 and 13) This valve as described inconnection wth FIG. 2, is

operated by the cam 39 on the cam shaft responsive to movement of thepedal 6 to the Brake Range. When the pedal 6 is in the Free-WheelingRange and Power Range, as represented in FIG. 2, the pressure balancedbrake valve spool 185, 188 will be biased by spring 186 against cam 39to assume the position shown in FIG. 13, whereby the return fluidflowing in passage 18 from the wheel motors 15 and from the returnpassage 18 of the direction control rvalve 17 will flow through thepassages 187 and 187A into the hot oil gallery 71, but as the pedal 6 isswung into the Brake Range (cam shaft 35 rotates counterclockwise asviewed in FIG. 13) the spring 186 will cause the brake valve spool 185to progressively decrease the cross-section size of the passages 187 and187A thereby restricting the return of fluid from the wheel motors 15and applying a braking action in proportion to the size of the openings187 and 187A. When the brake is fully applied, the brake valve spool 185substantially closes the passages 187 so that full braking elfect isexerted on the wheel motors 15 except for slight leakage through theannular gap between the land 188 and the bore 189 of the ported sleeve190.

It is to be noted that the heating of the fluid due to the brakingaction is remote from the wheel motors 15, that is, it is at thethrottled openings 187 and 187a in the brake valve 21 and as heat isgenerated, it is promptly dissipated by the heat exchanger 22 which isclosedly adjacent to the hot oil gallery 71.

The pilot operated relief valve 24 (FIGS. 2, 3, 4 and 14) The valve bodyis formed in the housing part 68 and the valve includes a spring-biasedmain valve member 195 which closes communication between the pump 10,delivery line 14 (or 14a and 14b) and the return line 13, except whenthe pressure in the delivery line exceeds a predetermined maximum safevalue which, for example, may be in the vicinity of 12,000 psi. In orderthat such main relief valve member 195 may employ a relatively softspring 196 and effect a prompt and large opening for such relief ofexcess pressure, there is provided in tandem therewith a pilot valveassembly 197 which includes a thimble portion 198 having an orifice 199therethrough and normally closed by the springbiased pilot valve member2110. The main valve195 also has an orifice 2G1 therethrough and whenthe pilot valve member 200 is in seated position, the pressures in thechambers 202 and 203 are equalized through the main valve orifice 201 sothat the main valve 195 is held in seated position by the relativelyweak spring 196. However, when the pressure in the chamber 203 acting onthe small exposed area of the pilot valve 200 exceeds the bias effect ofthe pilot valve spring 204, the pilot valve 200 is urged to openposition to vent the chamber 203 by way of the passage 205 at a ratewhich is greater than that at which fluid can be replenished throughorifice 201 into the chamber 2133 from the main valve chamber 202. Whenthis occurs there will be a pressure differ- 1Q ential between thechambers 202 and 203 such that the biasing effect of the main valvespring 1% is overcome, whereby the main valve is urged by thepredominating pressure in the chamber 2112 toward the right, as viewedin FIG. 14, to relieve such excess pressure building up in the deliverysystem 14A and 1413 from the variable capacity pump 11) through passages206 and 205 into the hot oil gallery 7 1.

The free-wheeling check valve 62 (FIGS. 2 20 6) As best shown in FIGS. 5and 6, this valve has an inlet port 210 communicating with sump 13, aseat 211, a check valve member 212 urged by spring 213 to closedposition (and also by fluid pressure in the pressure inlet passage 14Bof the direction control value), and an outlet port 214 leading topassage 14B. Thus, whenever the wheels 2 are turning faster than thefluid from pump 10 flows into the motors 15, the deficiency is made upby opening of the valve member 212 under the influence of negativepressure in passages 14B and 214 which permits the then predominatingpressure of the fluid in the sump 13 to force the valve member 212 awayfrom seat 211. This occurs also when the pedal 6 is moved to theFree-Wheeling Range while the vehicle 1 is in motion.

Throttle operation (FIGS. 1 and 2) As shown in FIG. 2, the enginethrottle valve 33 is linked to a cam member or lever 37 which has a camgroove of configuration as shown to open the throttle in the mannerrepresented by the curve 215 in FIG. 25, which, in conjunction with theother controls effects a pressure increase in accordance with the curve124 and an rpm. increase in accordance with the curve 216. Also, thebraking curve 213 shown in FIG. 25 is preferably a straight linefunction with percentage of braking power correlated with the degree ofmovement of the pedal 6. Of course, as already mentioned in connectionwith FIG. 2, the cam link 37 is actuated by the cam 36 on the cam shaft35 in accordance with the movement of the operating pedal 6.

II. The wheels 2 and wheel motors 15 (FIGS. 16, 17, and 21 I024!) Asalready described in connection with FIG. 2, the wheels 2 are rotatableon the generally horizontally ex tending portions 31 of the mountingstruts 32 and in the case of the front wheels, the struts are: providedwith steering levers 33. Referring now in detail to the Wheel and wheelmotor construction, there is provided a wheel rim 220 which may be ofconventional form, that is, it may be of the drop-center type includingside flanges 221 and base flanges 222 constituting supports for thebeads 2235 of a pneumatic tire 224, such tire herein being shown as atubeless tire. Said rim 220 also has a drop-center well 225 operative inwell-known manner to facilitate mounting and demounting of the tire 224.Welded, or otherwise secured, to the wheel rim 22% is a mounting ring226 formed with a plurality of holes through which extend the wheelmounting studs 227, said studs accommodating the nuts 228 which areoperative to mount the wheel rim 220) in place on the body 229 of thewheel 2. The, body 229 of the wheel, in this case, is the body of ahydraulic motor 15 which has a plurality of radial plungers 234 thereinwhich are biased inwardly by springs 231 against the periphery of theeccentric 232, the latter being supported on needle bearings 233 on thefixed shaft 31 through which fluid under pressure enters passage 20A or19A on one side or the other of the partition 2% and through which fluidreturns back to the sump 13 as aforesaid through the passage 19A or 20Aon one side or the other of the partition 234. When pressure entersthrough passage 211A, the wheel 2 will be driven by motor 15 in forwarddirection and when pressure enters through passage 19A the wheel will bedriven by motor 15 in reverse direction.)

' pump 10 inlet in that it is pressure-balanced.

sear/n The valving arrangement is similar to that used at The body 229is formed with radiating passages 239 that register with passages 240formed in the ported sleeve 241 that is press-fitted or keyed in thebody 229, said passages 239 leading to the respective plunger chambers242 to force the plungers inward against the eccentric 232 when thepassages are communicated with a fluid pressure source and to displacethe fluid from the chambers 24-2 and through passages 239 and 2% to sump13 when the plungers are forced outwardly by the eccentric 232. To socommunicate successive passages 239 and 240 with the pressure source andwith the sump, the fixed shaft 31 is formed with-passages 243 and 244leading to passages 19A and 212A therein.

As best shown in the developed views, FIGS. 23 and 24, the shaft 31 hastwo sets of slots 245 on either side of the passages 243 and 244- whichare connected by passages 246 to opposite passages 243 and 244, and thesleeve has two sets of openings 24-7 of aggregate area of the respectivepassages 2 50. Therefore, the sleeve 241 will turn freely on the shaft31 irrespective of the magnitude of the fluid pressure.

The body 229 and closure 249 assembly is rotatably supported on shaft 31by needle bearings 250 and by ball bearing 251. The bearings and idlemotor chambers are vented through passage 252 which is adapted forconnection with sump 13.

When the wheel 2 is to be driven in the forward direction, fiuid underpressure enters certain ones of the passages 240 and 239 leading to therespective plunger chambers 242 to force the plungers 23h inward whenthey are at a position on one side of dead center of the eccentric 232.When the wheel 2 is to be driven in reverse direction the fluid underpressure enters through the certain ones of the passages 24th and 239 toact on the plungers 23%) that bear on the eccentric 232 on the otherside of dead center to force the plungers 2350 inwardly and by reactionwith the eccentric 232 cause reverse rotation of the wheel.

As aforesaid, when it is desired to brake the wheels 2, the returnpassage 18 (FIG. 2) is blocked by the brake valve 21 and the extent ofblocking or restriction of the return flow determines the braking effectto gradually slow down or quickly stop the vehicle 1.

III. Alternative structures-Positioning of the valve 54 by manifoldvacuum instead of by the operators foot pedal 6 (FIGS. 25 to 28) Asshown in FIG. 25, the structure is basically the same as FIGS. 2-5, withthe exception that the valve 269 is positioned by manifold vacuumapplied in the chamber 261 against a spring-biased diaphragm 262 andthat the throttle valve 263 is positioned by direct mechanical linkage264 with the operators foot pedal through the pedal operated member 255,there being no need for the cam 46 shown in FIGS. 2 and 12. The orifice266, and chambers 267 and 268 correspond respectively with orifice 142and chambers 55 and 55 shown in FIGS. 2 and 12.

In FIG. 25, the brake valve 269 is operated by member 255 which islinked to the operators pedal in such manner that when member 265 movesto the left, the fluid from the direction control valve 17 connectedwith port 2749 is constricted as it flows past valve 269 to the sumpport 271.

The curve 275 in FIG. 26 shows the desired relationship between enginer.p.m. and the servo pressure in the chambers at the ends of the valve47. The curve 276 in FIG. 27 shows the relationship between engine rpm.and manifold vacuum. The curve 277 in FIG. 28, is a crossplot of thecurves 275 and 27a, and shows the relationship desired for manifoldvacuum versus control pressure in the chamber 268 (chamber 56 in FIG.2). This relationship is obtained through proper selection of thefollowing variables as indicated on FIG. 25, viz., the

area of the diaphragm 262, the rate and load of the spring 278, the sizeof the orifice 266, and the contour of the valve 260 and the size of thevalve seat.

Referring to FIG. 27, the point 280 corresponds to zero throttle valveopening, the point 281 corresponds to approximately 50% throttle valveopening, the point 282 corresponds approximately to throttle valveopening and the point 283 corresponds to throttle valve opening, thecurve 284 illustrating the relationship of manifold vacuum versus enginer.p.m. for a constant throttle opening of approximately 50%. Curvessimilar to curve 284 may be plotted for other throttle valve openings.Assuming steady operation at point 281, the 50% throttle valve openingto be at 50 mph. on level road under this condition, the pressures inthe chambers of valve 47 are equal and the valve therein is centered.Assuming that the vehicle starts up a hill, but that the operator doesnot change the position of the pedal 6, as the vehicle starts up thehill the extra load imposed thereby will cause the engine r.p.m. andmanifold vacuum to decrease along the constant throttle line togetherwith a reduction in vehicle speed. The decrease in r.p.m. reduces thepressure in the chamber 267 of valve 47 in accordance with the curve 275while the reduction in manifold vacuum increases the pressure in thechamber 268 in accordance with the curve 277. These pressure changescause the valve 47 to move to the right in FIG. 25 and thereby reducethe capacity and power of the engine driven pump 10. This allows theengine to increase r.p.m. and manifold vacuum along the curve 284 untilthe pressures are again equalized at the point 281 on curve 276. At thistime, the vehicle speed will be less than 50 mph. by an amountproportional to the grade of the hill.

On the other hand, if the operator wants to maintain a speed of 50 mph.while climbing the hill, all that he would have had to do was to depressthe pedal 6 and thereby open the throttle valve 263 a suficient amountto obtain the extra power required. By way of example, it is assumedthat the throttle valve opening giving the manifold vacuum at point 282would have been correct and that the throttle 263 is now opened to thispoint. Concurrently, with the opening of the throttle from point 281 topoint 282 the manifold vacuum decreases to the value shown at point 282.The lower vacuum permits the spring 278 to urge the diaphragm 262 to theright and thereby results in the valve 260 moving in a direction todecrease the flow through its seat thereby raising the pressure in thechamber 268 in accordance with the curve 277. Thus, momentarily thepressure in the chamber 268 is greater than in the other chamber 55 andthe valve 47 is moved to the right and reduces the capacity and power ofthe engine driven pump 14 This allows the engine rpm. to increasethereby concurrently increasing the pressure in the chamber 55 and whenthe engine r.p.m. has increased to the value corresponding to point 282the pressure in chamber 55 will have increased to an amount which equalsthe pressure in the chamber 268 and the valve 47 again will be centered.Under this new condition of pressure balance, the power delivered by theengine will be greater by an amount proportional to the decrease inmanifold vacuum and the increases in r.p.m. This increase in power isthat which was required to maintain the vehicle speed at 50 mph. whileclimbing the hill.

Power for acceleration is obtained in a similar manner and it can beseen that by flooring the foot pedal 6, the engine power associated withfull throttle and rated r.p.m. is instantly available for accelerationat any vehicle speed thereby providing more power for acceleration thanit attainable with any known transmission system in use.

Other modes of applying the principle of the invention may be employed,change being made as regards the details described, provided thefeatures stated in any of 13 the following claims or the equivalent ofsuch be employed.

I, therefore, particularly point out and distinctly claim as myinvention:

1. A variable capacity pump comprising a housing; radial plungersreciprocable in said housing; a drive shaft journalled in said housing;an eccentric on said drive shaft engaging said plungers to move them;said housing being formed with an intake port adapted to be connected toa sump and a delivery port; rotary intake valving driven by said driveshaft successively to communicate said plungers with said intake portwhen said plungers move in one direction; an outlet valve in saidhousing successively to communicate said plungers with said deliveryport when said plungers move in an opposite direction; a spill passageadapted to be connectedto such sump, and fluid pressure actuatedcapacity varying means in said housing effective to control fluid flowthrough said spill passage to such sump during predetermined portions ofthe strokes of said plungers according to the magnitude of the fluidpressure acting on said capacity varying means.

2. The pump of claim 1 wherein said rotary intake valving isfluid-pressure balanced.

3. The pump of claim 1 wherein said capacity varying means comprises asleeve-type valve for each plunger which is spring-biased to zerocapacity position.

4. In a power transmission system for a prime mover having an associatedcontrol means to vary the speed and power output of the prime mover; avariable capacity pump comprising a housing; radial plungersreciprocable in said housing; a drive shaft journalled in said housingadapted to be driven by the prime mover; an eccentric on said driveshaft engaging said plungers to move them; said housing being formedwith an intake port adapted to be connected to a sump, and a deliveryport; rotary intake valving driven by said drive shaft successively tocommunicate said plungers with said intake port when said plungers movein one direction; an outlet valve in said housing successively tocommunicate said plungers with said delivery port when said plungersmove in an opposite direction; a spill passage adapted to be connectedto such sump, and fluid pressure actuated capacity varying means in saidhousing effective to control fluid flow through said spill passage tosuch sump, during predetermined portions of the strokes of said plungersaccording to the magnitude of the fluid pressure acting on said capacityvarying means.

5. The power transmission system of claim 4 wherein said capacityvarying means comprises a sleeve-type valve for each plunger which isspring-biased to zero capacity position.

6. The power transmission system of claim 5 wherein said prime movercomprises an internal combustion engine including an intake manifold,and the position of said sleeve-type valve is responsive to the manifoldvacuum of said prime mover.

7. The power transmission system of claim 4 wherein said rotary intakevalving is fluid-pressure balanced.

8. A variable capacity pump comprising a housing, radially extendingplungers reciprocable in said housing, a drive shaft journalled in saidhousing, an eccentric on said drive shaft operative to reciprocate saidplungers, said housing being formed with an intake port adapted to beconnected to a sump, and a delivery port, rotary intake valving drivenby said drive shaft successively to communicate said plungers with saidintake port when said plungers move in one direction; a spill passageadapted to be connected to such sump, and fluid pressure actuatedcapacity varying means in said housing operative to control fluid flowthrough said spill passage to such sump for a predetermined portion ofthe strokes of said plungers according to the magnitude of fluidpressure acting on said capacity varying means.

9. A pump as set forth in claim 8 wherein said capacity varying meanscomprises a movable sleeve surrounding each plunger, a spill groove ineach plunger communicating with said spill passage for a portion of thestroke of said plunger depending on the position of said sleeve.

10. A pump as set forth in claim 9 including fluid pressure means actingon said sleeve tending to move said sleeve to shorten the portion of thestroke of said plunger wherein said spill groove will be exposed to saidspill passage to increase the capacity of said pump.

11. A pump as set forth in claim 10 including spring means acting onsaid sleeve opposing said fluid pressure means tending to move saidsleeve to increase the portion of the stroke of said plunger whereinsaid spill groove will be exposed to said spill passage to decrease thecapacity of the pump.

12. The pump of claim 8 wherein said rotary intake valving comprises asleeve, multiple passages in said sleeve operative to communicate saidplungers with said intake port when said plungers move in one direction,pairs of static 'holes in said sleeve diametrically opposite eachpassage, and groove means in said sleeve connecting each passage and thepair of holes diametrically opposite thereto to balance out the fluid.forces on said sleeve.

13. A variable capacity pump comprising a housing, radially extendingplungers reciprocable in said housing, a drive shaft journalled in saidhousing, means operative to reciprocate said plungers, said housingbeing formed with an intake port adapted to be connected to.a sump, anda delivery port, a spill passage, capacity varying means in said housingactuated by fluid pressure imposed directly thereon operative to controlfluid flow through said spill passage to such pump for a predeterminedportion of the strokes of said plungers according to the magnitude offluid pressure acting directly on said capacity varymg means.

References Cited by the Examiner UNITED STATES PATENTS 1,440,428 1/ 1923Wigelius 103-37 1,508,054 9/ 1924 Hoppins 103-37 1,642,103 9/ 1927Daubenmeyer -66 1,657,841 1/1928 Peris 251-283 2,251,783 8/1941 Davis103-41.1 2,319,566 5/ 1943 Sunderman 103--41.1 2,372,523 3/ 1945Sinclair 103-174 2,418,123 4/1947 Joy 180-66 2,433,222 12/1947 Huber103-173 2,494,505 1/1950 Bouchrad 180-54.3 X 2,524,235 10/1950 Schenk103-41 2,535,617 12/ 1950 Westbrook 103-12 2,545,220 3/1951 Wolcott251-283 2,640,372 6/1953 Dodge 74-472.1 2,650,573 9/1953 Hickman 60-53 X2,786,424 3/ 1957 Raymond 103-174 2,875,635 3/ 1959 Fleck et a1.74-472.] 2,889,780 6/1959 Binford 103-12 2,945,451 7/ 1960 Griswold103-174 3,059,416 10/1962 Campbell 180-60 X FOREIGN PATENTS 893,2131/1944 France.

578,985 6/1933 Germany.

459,578 1/ 1937 Great Britain.

LAURENCE V. EFNER, Primary Examiner. G. HARRY LEVY, Examiner.

M. L. SMITH, Assistant Examiner.

1. A VARIABLE CAPACITY PUMP COMPRISING A HOUSING; RADIAL PLUNGERSRECIPROCABLE IN SAID HOUSING; A DRIVE SHAFT JOURNALLED IN SAID HOUSING;AN ECCENTRIC ON SAID DRIVE SHAFT ENGAGING SAID PLUNGERS TO MOVE THEM;SAID HOUSING BEING FORMED WITH AN INTAKE PORT ADAPTED TO BE CONNECTED TOA SUMP AND A DELIVERY PORT; ROTARY INTAKE VALVING DRIVEN BY SAID DRIVESHAFT SUCCESSIVELY TO COMMUNICATE SAID PLUNGERS WITH SAID INTAKE PORTWHEN SAID PLUNGERS MOVE IN ONE DIRECTION; AN OUTLET VALVE IN SAIDHOUSING SUCCESSIVELY TO COMMUNICATE SAID PLUNGERS WITH SAID DELIVERYPORT WHEN SAID PLUNGERS MOVE IN AN OPPOSITE DIRECTION; A SPILL PASSAGEADAPTED TO BE CONNECTED TO SUCH SUMP, AND FLUID PRESSURE ACTUATEDCAPACITY VARYING MEANS IN SAID HOUSING EFFECTIVE TO CONTROL FLUID FLOWTHROUGH SAID SPILL PASSAGE TO SUCH SUMP DURING PREDETERMINED PORTIONS OFTHE STROKES OF SAID PLUNGERS ACCORDING TO THE MAGNITUDE OF THE FLUIDPRESSURE ACTING ON SAID CAPACITY VARYING MEANS.